The present invention relates to the insertion of catheters into blood vessels.
It is common in the medical arts to insert catheters into blood vessels for various purposes such as pressure monitoring and parenteral infusion. As a result, a variety of techniques and devices for accomplishing the insertion are known. In one general method, catheters are inserted by the provision of a stiff needle that is located interior to and coaxial with the catheter and extends out its front end. The catheter is thereby inserted with the needle, and the needle may or may not be retracted following the insertion. Another general method employs a somewhat larger-diameter needle with the catheter carried inside.
The method and apparatus of the present invention are directed to still another general method, in which a guide wire is first inserted into the vein. The free end of the wire is threaded through the central passage of a catheter having a beveled forward edge, and the catheter is then inserted by being fed along the guide wire. This general method has numerous advantages, but part of the technique has been found both inconvenient for the medical personnel and unpleasant for the patient. It is necessary after the needle employed in this method has been inserted to retract it somewhat to determine that the intended blood vessel has been reached. This usually involves a fair amount of bleeding at the site of the insertion, which complicates the procedure for the doctor and can be disconcerting to the patient. Accordingly, it is an object of the present invention to test for proper positioning of the needle without the bleeding that has heretofore attended this technique.